It will be appreciated that the roasting level of coffee beans can be determined during coffee roasting and further used to determine roasting process.
Traditionally, the coffee beans are roasted manually. The heating power and time are always predetermined. Sometimes, professionals monitor the surface colour change of the coffee beans during roasting process, then control or adjust coffee roasting profile (e.g. heating power, heating time, etc.) accordingly based on their professional experience. However, a lot people, especially those ordinary consumers, are always incapable of accurately and quantitatively determining the roasting profile. They don't know how to judge the roasting degree and how to adjust roasting profile according to real status. Thus, the roasting process would suffer from human errors (e.g. coffee bean over burn).
DE19645306 A1 discloses a device for controlling the roasting process for roasting coffee automatically, in particular for measuring the color value of coffee beans located in the roaster. It comprises an optical access in the roaster allowing to window in a sight glass, and an evaluation device for the control of the coffee roasting based on the measured color value of the roasted coffee, and to terminate automatically the roasting process on reaching a preselected roasting degree of coffee.
Either for professionals or for a device with an optical access to measure the color value of the roasted coffee beans, it is not easy to determine the right roasting profile during roasting process. Although it is known that surface colour of coffee beans is an important indicator to determine the roasting level of coffee beans, as the surface colour becomes darker during roasting, only surface colour itself is still not sufficient to determine the roasting degree. Coffee beans with same surface colour may provide different final taste to consumer, because coffee beans with same surface colour may have different colour of inner part due to different bean type or roasting profile.
In view of the foregoing, there is a need to provide a more accurate and automatic solution for controlling a roasting process of coffee beans.